Abstract

SALCEDO, Octavio; LOPEZ, Danilo  and  HERNANDEZ, Cesar. A comparative study of bandwidth usage running protocols SIP and IAX. Tecnura [online]. 2012, vol.16, n.34, pp.171-187. ISSN 0123-921X.

Within the VoIP networks environment, there are three protocols that solve the problem of voice packet signaling, known as "highlight protocols": H323, SIP and IAX. Particularly, this document focuses on a specific difference between SIP and IAX: the bandwidth usage, which is an essential parameter in order to design and optimize a VoIP network for an organization. One of the most important factors to consider when building VoIP networks is proper planning capacity. About planning capacity, bandwidth calculation is an important factor to consider when designing and troubleshooting packet voice networks for good voice quality. This paper presents important explanations about the bandwidth utilization over VoIP networks; this includes some theoretical foundations and bandwidth calculation on a perfow basis for a VoIP trunk, in which different voice codecs are enabled (specifically G.711 and GSM) together with VoIP protocols such as SIP and IAX. Voice over IP (VoIP) is applied. These calculations are compared against the results obtained from traffic analyzers over a physical Ethernet trunk between two Asterisk servers into a specific LAN, simulating two different branches of an organization. Both the analysis of the results obtained and the conclusions from this work are useful when calculating the maximum number of simultaneous calls or the minimum capacity of a data link that is necessary for a particular number of voice conversations, taking into account the audio codecs used and the signaling and data fow protocols.

Keywords : Bandwidth; audio; codec; IAX; SIP; VoIP.

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